arch/mips/ralink/early_printk.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  *  Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>
   5  */
   6
   7 #include <linux/io.h>
   8 #include <linux/serial_reg.h>
   9
  10 #include <asm/addrspace.h>
  11 #include <asm/setup.h>
  12
  13 #ifdef CONFIG_SOC_RT288X
  14 #define EARLY_UART_BASE         0x300c00
  15 #define CHIPID_BASE             0x300004
  16 #elif defined(CONFIG_SOC_MT7621)
  17 #define EARLY_UART_BASE         0x1E000c00
  18 #define CHIPID_BASE             0x1E000004
  19 #else
  20 #define EARLY_UART_BASE         0x10000c00
  21 #define CHIPID_BASE             0x10000004
  22 #endif
  23
  24 #define MT7628_CHIP_NAME1       0x20203832
  25
  26 #define UART_REG_TX             0x04
  27 #define UART_REG_LCR            0x0c
  28 #define UART_REG_LSR            0x14
  29 #define UART_REG_LSR_RT2880     0x1c
  30
  31 static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);
  32 static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE);
  33 static int init_complete;
  34
  35 static inline void uart_w32(u32 val, unsigned reg)
  36 {
  37         __raw_writel(val, uart_membase + reg);
  38 }
  39
  40 static inline u32 uart_r32(unsigned reg)
  41 {
  42         return __raw_readl(uart_membase + reg);
  43 }
  44
  45 static inline int soc_is_mt7628(void)
  46 {
  47         return IS_ENABLED(CONFIG_SOC_MT7620) &&
  48                 (__raw_readl(chipid_membase) == MT7628_CHIP_NAME1);
  49 }
  50
  51 static void find_uart_base(void)
  52 {
  53         int i;
  54
  55         if (!soc_is_mt7628())
  56                 return;
  57
  58         for (i = 0; i < 3; i++) {
  59                 u32 reg = uart_r32(UART_REG_LCR + (0x100 * i));
  60
  61                 if (!reg)
  62                         continue;
  63
  64                 uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE +
  65                                                           (0x100 * i));
  66                 break;
  67         }
  68 }
  69
  70 void prom_putchar(char ch)
  71 {
  72         if (!init_complete) {
  73                 find_uart_base();
  74                 init_complete = 1;
  75         }
  76
  77         if (IS_ENABLED(CONFIG_SOC_MT7621) || soc_is_mt7628()) {
  78                 uart_w32((unsigned char)ch, UART_TX);
  79                 while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)
  80                         ;
  81         } else {
  82                 while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
  83                         ;
  84                 uart_w32((unsigned char)ch, UART_REG_TX);
  85                 while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
  86                         ;
  87         }
  88 }